It is not your imagination but I think it depends on the clutch ratings of the players.
I also devote 6 weeks to playing a full season, I was rocked the first game of the division series but somehow got through it, then subsequent series were easier/like playing the regular season. I think it’s because my team was just rated higher than my “opponents”.
It is annoying as hell to play a good game only to have the CPU score at will, which is what seems to be the case when I lose. With experience you can gauge when the CPU is going to hammer you, the one bit of damage control that seems to work often is pulling your starting pitcher as soon as this happens. I say this as someone who has played thousands of games as a 10+ year player.
This theory might be because in real life starting pitchers, especially in the playoffs, often don’t get credit for a win they started - so perhaps there is something in the programming where if you’ve had success with a starter, he’s bound to lose eventually or get a no decision. I found that if I pull my starter as soon as he gets rocked, there is a good chance I can win the game despite being down 3-5 runs because I begin hitting again and scoring runs. In a scenario like this, the only conclusion I can come up with is I had a chance to win, it’s just that my starter is 15-3 and it’s just “his turn” to lose the game statistically speaking, but perhaps when he’s pulled he’ll get a no decision if I’m able to start hitting again with a new pitcher from the bullpen.
Anyway sorry if this is long winded but I think this is how the CPU operates. Drop your starter if he gets rocked no matter how early, and you’ll have a better probability of coming back using the bullpen.